How Do You Calculate an Extension Spring's Load?
Koj xav tau lub caij nplooj ntoos hlav uas rub nrog lub zog tshwj xeeb, tab sis koj cov kev suav tsis raug. Cov khoom xav tias xoob dhau los yog nruj dhau, thiab koj pheej hmoo rau tus qauv tsim uas tsis muaj kev ntseeg siab lossis ua tsis tiav.
Tag nrho cov load ntawm lub caij nplooj ntoos hlav txuas ntxiv yog suav nrog cov qauv no: Load = (Caij nplooj ntoos hlav tus nqi × Mus txawv tebchaws) + Kev Nyuaj Siab[^ 1]n](https://www.acxesspring.com/initial-tension-in-extension-springs.html?srsltid=AfmBOoqIOZdbYGa2dxloEt1N1MVBsBVWbRRAne-8F6W4-_GoP9_Vgr3o)[^2]. Qhov no suav nrog ob lub zog los ntawm kev ncab thiab lub zog ua ntej ua ntej ua rau lub caij nplooj ntoos hlav.
Hauv kuv 14 xyoo ntawm kev pab engineers tsim kev cai springs, qhov feem ntau ntawm qhov yuam kev yog tsis nco qab ib feem ntawm cov qauv yooj yim ntawd. Ntau tus neeg tsuas yog tsom mus rau lub caij nplooj ntoos hlav tus nqi thiab nws ntev npaum li cas, kiag li ignoring thawj zaug nro. Qhov kev quab yuam zais no feem ntau yog qhov sib txawv ntawm lub tshuab uas hnov lus teb thiab ib qho uas hnov sloppy thiab pheej yig. Cia peb kawm seb yuav ua li cas thiaj li tau txais qhov kev suav no yog txhua lub sijhawm.
What's the Fundamental Formula for Spring Load?
Koj xam lub zog siv lub caij nplooj ntoos hlav tus nqi thiab nyob deb. Tam sim no, koj lub cev qauv xav tau ntau lub zog los ua haujlwm tshaj qhov koj xav tau, pov tawm koj tus tsim tag nrho.
Tus qauv raug yog Load = (Caij nplooj ntoos hlav tus nqi × Mus ncig teb chaws) + Kev Nyuaj Siab. Koj yuav tsum ntxiv qhov pib pre-load (Kev Nyuaj Siab) rau lub zog tsim los ntawm stretching (Caij nplooj ntoos hlav tus nqi × Mus ncig teb chaws) nrhiav qhov tseeb tag nrho.
Kuv nco qab ua haujlwm nrog kev pib ua haujlwm uas tab tom tsim ib qho tshiab ntawm cov khoom siv qoj ib ce. Lawv cov qauv siv rau lub caij nplooj ntoos hlav muab ib tug du, nce kev tiv thaiv. Lawv thawj prototypes xav tias txaus ntshai. Muaj ib tug “Zoo tuag" thaum pib ntawm rub ua ntej muaj kev tawm tsam tiag tiag ncaws tawm. Lawv tau hnov qab tag nrho txog qhov kev sib tw thawj zaug hauv lawv cov kev suav. Lawv tsuas suav rau lub caij nplooj ntoo hlav xwb. Peb rov tsim kho lub caij nplooj ntoos hlav nrog rau qhov tshwj xeeb pib nro tus nqi. Qhov no ua kom tus neeg siv xav tias tam sim ntawd tsis kam, thiab tag nrho cov load ntawm tag nrho extension matched lawv lub hom phiaj. Qhov kev hloov ntawd ua rau cov khoom xav tias muaj kev tshaj lij thiab zoo.
Peb Qhov Tseem Ceeb Variables
Los xam cov load, koj yuav tsum to taub peb qhov tseem ceeb. Txhua tus ua lub luag haujlwm tseem ceeb hauv kev ua haujlwm kawg ntawm lub caij nplooj ntoo hlav.
- Caij nplooj ntoos hlav Rate (k)[^3]: This is the spring's stiffness, ntsuas nyob rau hauv quab yuam ib unit ntawm kev ncua deb (E.G., lbs/inch los yog N/mm). Nws qhia koj ntau npaum li cas ntxiv quab yuam rau txhua nti lossis millimeter koj ncab lub caij nplooj ntoos hlav.
- Mus ncig (X)[^4]: Qhov no yog qhov kev ncua deb lub caij nplooj ntoos hlav tau ncab los ntawm nws so, los yog "dawb," ntev.
- Kev Nyuaj Siab[^2] (IT): Qhov no yog lub zog uas yog coiled rau lub caij nplooj ntoos hlav thaum tsim khoom. It's the load you must apply just to separate the coils before it even starts to stretch.
| Hloov pauv | Cim | Kev piav qhia |
|---|---|---|
| Caij nplooj ntoos hlav Rate | k | Lub zog ntawm lub caij nplooj ntoos hlav. |
| Mus ncig deb | X | Ntev npaum li cas lub caij nplooj ntoos hlav stretched los ntawm nws qhov ntev dawb. |
| Kev Nyuaj Siab[^2] | IT | Tus pre-loaded quab yuam[^ 5] tuav cov coils ua ke thaum so. |
Yog vim li cas Kev Nyuaj Siab[^2] Feem ntau yuam kev?
Your spring isn't engaging when you need it to. Nws muaj qhov pom kev lag luam ua ntej nws pib rub, uas ua rau tus cwj pwm tsis sib haum xeeb hauv koj mechanical sib dhos[^6].
Qhov kev lag luam no yog vim qhov qis lossis miscalculated pib nro. Qhov no pre-load quab yuam yog feem ntau overlooked variable, tsis tau nws txiav txim siab load yuav tsum ua ntej lub caij nplooj ntoos hlav txawm pib ncab, directly impacting the system's responsiveness.
One of the clearest examples I've seen was for a simple screen door closer. A hardware company came to us because their new door closers weren't working. The doors wouldn't fully latch shut. Lub caij nplooj ntoos hlav lawv tsim muaj lub caij nplooj ntoos hlav muaj zog txaus, tab sis nws yuav luag tsis muaj qhov pib nruj. Qhov no txhais tau tias rau ob peb ntiv tes dhau los ntawm kev mus ncig, raws li lub caij nplooj ntoos hlav tau luv, lub load poob mus yuav luag xoom. Tsis muaj qhov kawg "snap" rub lub qhov rooj rau hauv lub latch. Peb tsim lub caij nplooj ntoos hlav tshiab nrog tus nqi tib yam tab sis ntxiv qhov tseem ceeb ntawm qhov pib nruj. Qhov kev hloov me me no tau muab qhov kev rub tas li xav tau los latch lub qhov rooj ruaj ntseg txhua lub sijhawm.
Qhov twg Qhov Kev Nyuaj Siab Pib Los Ntawm
Thaum pib nro tsis yog kev huam yuaj; nws yog ib qho tshwj xeeb txhob txwm tsim thaum lub sij hawm tsim khoom.
- Txoj Kev Coiling: Raws li lub caij nplooj ntoos hlav hlau yog coiled ntawm lub tshuab, nws yog twisted me ntsis. Qhov no torsional kev nyuaj siab[^7] yog dab tsi nias lub coils nruj nreem rau ib leeg.
- Rooj mov: Qhov kev siv zog ua haujlwm no muaj txiaj ntsig zoo rau ntau daim ntawv thov. Nws ua kom cov rooj sib txoos nruj, tiv thaiv rattling los ntawm kev vibration, thiab kom a mechanism yog tuav ruaj ntseg[^8] nyob rau hauv nws qhov chaw so. Tag nrho lub zog ntawm koj lub caij nplooj ntoos hlav yog ib txwm suav ntawm qhov pib quab yuam ntxiv rau lub zog ntawm ncab.
| Yam | Lub Caij Nplooj Ntoos Hlav nrog High Initial Tension | Caij nplooj ntoos hlav nrog qis Kev Nyuaj Siab[^2] |
|---|---|---|
| Thaum So | Coils tau tuav ua ke nruj heev. | Coils yog kov tab sis cais yooj yim. |
| Pib rub | Yuav tsum muaj lub zog tseem ceeb tsuas yog pib ncab. | Yuav tsum muaj zog me ntsis los pib ncab. |
| Siv dav | Screen qhov rooj, tus tshaj cum, retractable systems. | Cov cuab yeej rhiab heev, counterbalance systems. |
Yuav ua li cas koj siv cov qauv rau ib tug tiag tiag-lub ntiaj teb no teeb meem?
Cov mis zoo li abstract. You're not confident about how to plug in your own numbers and get a reliable answer for your specific application, ua rau qeeb hauv koj qhov project.
Koj tuaj yeem siv cov qauv hauv ib qho yooj yim, txheej txheem txheej txheem. Ua ntej, define your spring's properties (tus nqi, pib nro, dawb ntev). Ces, txiav txim siab koj lub sijhawm ua haujlwm los xam kev mus ncig. Kawg no, ntxig cov nqi no rau hauv cov qauv.
Tsis ntev los no peb tau ua hauj lwm nrog ib tus kws kho tsheb tsheb uas tau tsim lub caij nplooj ntoos hlav-loaded latch rau lub hnab looj tes. Cov specifications tau meej heev. Lub latch xav tau kom muaj kev ruaj ntseg tab sis kuj tseem qhib tau yooj yim. Tus kws ua haujlwm tau muab peb lub nra hnyav uas lawv xav tau ntawm txoj haujlwm latched tag nrho. Peb siv cov qauv kev suav load nyob rau hauv thim rov qab. Peb paub qhov yuav tsum tau thauj khoom thiab kev mus ncig, yog li peb tuaj yeem ua haujlwm rov qab los qhia qhov zoo tshaj plaws ua ke ntawm lub caij nplooj ntoos hlav tus nqi thiab pib nro. Qhov no "design-by-calculation" txoj kev cawm tau ntau qhov kev sim thiab ua yuam kev nrog lub cev qauv thiab tau txais lawv mus rau qhov kawg, ua hauj lwm feem ntau sai dua.
Ib kauj ruam-los-kauj ruam piv txwv
Let's walk through a complete example.
Xav txog tias koj muaj lub caij nplooj ntoos hlav nrog cov lus qhia hauv qab no:
- Free Length (L₀): 2 ntiv tes
- Caij nplooj ntoos hlav Rate (k)[^3]: 10 lbs/inch
- Kev Nyuaj Siab (IT): 5 lbs
Lus nug: Tag nrho cov load yog dab tsi thaum lub caij nplooj ntoos hlav stretched mus rau ib tug ncua ntev (L₁) ntawm 6 ntiv tes?
-
Xam qhov Kev Ncig Mus Los (X):
Travel = Extended Length - Free Length
X = 6 inches - 2 inches = 4 inches -
Xam qhov Load los ntawm Stretching:
Load from Travel = Spring Rate × Travel
Load from Travel = 10 lbs/inch × 4 inches = 40 lbs -
Muab xam tag nrho Load:
Total Load = Load from Travel + [Initial Tension](https://www.acxesspring.com/initial-tension-in-extension-springs.html?srsltid=AfmBOoqIOZdbYGa2dxloEt1N1MVBsBVWbRRAne-8F6W4-_GoP9_Vgr3o)[^2]
Total Load = 40 lbs + 5 lbs = 45 lbs
Cov lus teb kawg yog 45 lbs.
| Kauj ruam | Calculation | Kev tshwm sim |
|---|---|---|
| 1. Nrhiav Mus ncig (X)[^4] | 6" (L₁) - 2" (L₀) |
4 inches |
| 2. Nrhiav Load los ntawm Travel | 10 lbs/inch (k) * 4" (X) |
40 lbs |
| 3. Nrhiav Tag Nrho Load | 40 lbs + 5 lbs (IT) |
45 lbs |
Tag
To calculate an extension spring's load, koj yuav tsum siv tag nrho cov mis. Ib txwm ntxiv qhov pib nro rau lub zog tsim los ntawm lub caij nplooj ntoos hlav tus nqi thiab mus rau qhov tseeb.
[^ 1]: Kev nkag siab txog cov qauv no yog qhov tseem ceeb rau kev tsim lub caij nplooj ntoos hlav thiab kev ua tau zoo.
[^2]: Kawm paub yuav ua li cas thawj zaug nro cuam tshuam rau lub caij nplooj ntoos hlav kev ua haujlwm thiab kev ua haujlwm hauv cov tshuab tshuab.
[^3]: Tshawb nrhiav seb lub caij nplooj ntoos hlav tus nqi cuam tshuam li cas rau qhov tawv thiab lub peev xwm thauj khoom ntawm cov springs.
[^4]: Kev nkag siab txog kev mus txawv tebchaws yog qhov tseem ceeb kom ntseeg tau tias koj lub caij nplooj ntoo hlav ua haujlwm zoo.
[^ 5]: Tshawb nrhiav qhov tseem ceeb ntawm pre-loaded quab yuam kom ua tiav qhov xav tau lub caij nplooj ntoo hlav.
[^6]: Kawm paub yuav ua li cas kev xam cov caij nplooj ntoos hlav caij nplooj ntoos hlav tuaj yeem txhim kho kev ntseeg tau ntawm cov khoom sib dhos.
[^7]: Torsional kev nyuaj siab yog qhov tseem ceeb los xyuas kom meej qhov zoo thiab kev ua tau zoo ntawm cov springs.
[^8]: Kawm txog qhov tseem ceeb ntawm cov springs hauv kev tswj kev ruaj ntseg thiab kev ua haujlwm hauv cov khoom siv.